ETR - Power transformers

IEC 60076-22-6:2021 covers the electric fans used in the cooling circuits of power transformers and reactors. It applies to electric fans mounted on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to all the equipment.
The electric fans concerned by this document are of the axially operating type and are for use on liquid to air coolers and for blowing out radiators.
This document also outlines the operation requirements specific to each equipment as well as the preferred dimensions relevant for interchangeability and uniform fan assembly and the type and routine tests to be performed.

IEC 60076-22-5:2021 covers electric pumps used in the cooling circuits of power transformers and reactors. It applies to electric pumps mounted on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation.
It outlines the operation requirements for the electrical and hydraulic performance, mechanical design, routine testing and type testing. Additionally, performance and dimensions of preferred sizes of pump sets are specified in informative annexes.
The pumps covered in this document are rotodynamic pumps driven by a squirrel cage induction motor that is immersed in the insulating liquid.
Pump sets conforming to this document can be of in-line or end suction design.

TC - Correction of technical errors

TC - Correction of technical errors

This document applies to medium power transformers from 25 kVA up to 3 150 kVA with highest
voltage for equipment up to 36 kV, or in low voltage (LV) networks with highest voltage for
equipment of up to 1,1 kV equipped with voltage regulating devices.
Voltage regulating distribution transformers are transformers equipped with components to
control primary or secondary voltage for on-load voltage regulation purposes.
The main objective of the installation of a VRDT is to regulate the LV network voltage level (i.e.
400 V), to avoid violation of the limits defined by relevant standards or regulations. The VRDT
must operate properly as a step down and step up transformer.
Transformers covered by this document comply with the relevant requirements set out in
IEC 60076 (all parts) and, unless otherwise stated in this document, they also comply with
European Standards EN 50160 and EN 50588-1.

This part of IEC 60076-22 applies to a selection of accessories and fittings mounted on liquid
immersed power transformers according to IEC 60076-1 and reactors according to IEC 600766
with or without conservator for indoor or outdoor installation. It outlines the service conditions
and the mechanical requirements that are common to all the accessories and fittings.
This document also outlines the operation requirements specific to each device as well as the
preferred dimensions relevant for interchangeability and the type and routine test to be
performed.
This document covers an exhaustive selection of the accessories and fittings that are currently
used on transformers or reactors.

The scope of this document is to define the energy performance of Medium Power Transformers in compliance with prEN 50708-1-1:2019.

This document is part of the of the EN 50708 series which applies to transformers in compliance with EN 60076 1.

The scope of this document is to define performance requirements of Large Power Transformers in compliance with prEN 50708 1 1:2019.
NOTE    This document covers the transformers under the EU Regulation N. 548/2014 and Amendment of 2019, gives additional specific guidance for single phase transformers, autotransformers, multi winding transformers and for transformers with OD and OF cooling systems, necessary for the correct application of energy efficiency requirements to these categories of transformers.

This standard applies to liquid to water heat exchangers, using forced water and forced liquid circuits, used on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to this equipment. It also outlines the operation requirements specific to this equipment as well as the preferred dimensions relevant for interchangeability and the type and routine tests to be performed.

This standard applies to liquid to air heat exchangers, using forced air and forced liquid circuits, used on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to this equipment. It also outlines the operation requirements specific to this equipment as well as the preferred dimensions relevant for interchangeability and the type and routine tests to be performed.

This standard applies to radiators mounted on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to this equipment. It also outlines the operation requirements specific to this equipment as well as the preferred dimensions relevant for interchangeability and the type and routine tests to be performed.

This part of IEC 60076-22 applies to protective devices mounted on liquid-immersed power
transformers in accordance with IEC 60076-1 and reactors in accordance with IEC 60076-6
with or without conservator for indoor or outdoor installation. It outlines the service conditions
and the mechanical and electrical requirements that are common to all the devices, which are
relevant for the safety of the machine having a function of signalization of abnormal operating
conditions.
It also outlines the operation requirements specific to each device as well as, in some cases,
the preferred dimensions relevant for interchangeability and the type and routine test to be
performed.

This part of IEC 60076 applies to dry-type power transformers (including auto-transformers)
having values of highest voltage for equipment up to and including 72,5 kV and at least one
winding operating at greater than 1,1 kV.
This document does not apply to:
• gas-filled dry-type transformers where the gas is not air;
• single-phase transformers rated at less than 5 kVA;
• polyphase transformers rated at less than 15 kVA;
• instrument transformers;
• starting transformers;
• testing transformers;
• traction transformers mounted on rolling stock;
• flameproof and mining transformers;
• welding transformers;
• voltage regulating transformers;
• small power transformers in which safety is a special consideration.
Where IEC standards do not exist for the transformers mentioned above or for other special
transformers, this document may be applicable as a whole or in parts.

EN 50588-2 covers, in conjunction with EN 50588-1, transformers under iii) and iv) above, up to 36 kV
(the data from 24 kV to 36 kV are under consideration) and for transformers with rated power less than
or equal to 3150kVA . Further documents exist which may be used by agreement between purchaser
and manufacturer for cable boxes and enclosures. The dimensional requirements for cable boxes and
protective enclosures are not enclosed in this document.

Cable boxes described in this European Standard correspond to cable boxes Type 2 in EN 50588-2
and are suitable for assembly on the cover of oil-immersed distribution transformers meeting the
requirements of EN 50588-2.
Cable boxes are air-filled, metal- or non-metal enclosed, for high- and/or low-voltage connections in the
following variations:
1.1 High-voltage side
a) Connection directly to bushings;
b) Connection via busbar system.
1.2 Low-voltage side
a) Connection directly to bushings (maximum of four connectors per bushing);
b) Connection via busbar system.

This European Standard specifies the requirements for cable boxes, Type 1, in which the cable cores
are terminated. The cable boxes are suitable for use on transformers defined in EN 50588-2,
“Transformers with Cable Boxes”, for side mounted or cover mounted use. The cable boxes are
suitable for operation indoors and outdoors under environmental conditions specified in EN 50588-1.
Important design and construction requirements of the cable boxes are given.

This European Standard applies to new three-phase and single-phase power transformers with a highest voltage for equipment exceeding 36 kV and a rated power equal or higher than 5 kVA, or a rated power equal to or higher than 40 MVA regardless of the highest voltage for equipment.
The scope of this European Standard is the following:
-   Defining the appropriate energy efficiency criteria;
-   Setting of benchmark minimum efficiency levels for new transformers based on an assessment of the energy efficiency of the European transformer population installed in the last 10 years;
-   Proposing higher minimum efficiency levels for improving the energy efficiency of new transformers;
-   Providing guidance for consideration of Total Cost of Ownership.
This European Standard provides also a form for efficiency data collection to inform future efficiency benchmark levels.
NOTE 1   This standard covers the transformers under the EU Regulation N. 548/2014 and gives additional specific indications for single phase transformers, auto transformers, multi winding transformers and for transformers with OD and OF cooling systems.
Transformers considered to be out of the scope of this document are the following:
-   instrument transformers, specifically designed to supply measuring instruments, meters, relays and other similar apparatus,
-   transformers with low-voltage windings specifically designed for use with rectifiers to provide a DC supply,
-   transformers specifically designed to be directly connected to a furnace,
-   transformers specifically designed for offshore applications and floating offshore applications,
-   transformers specially designed for emergency installations,
-   transformers and auto-transformers specifically designed for railway feeding systems,
-   earthing or grounding transformers, this is, three-phase transformers intended to provide a neutral point for system grounding purposes,
-   traction transformers mounted on rolling stock, this is, transformers connected to an AC or DC contact line, directly or through a converter, used in fixed installations of railway applications,
-   starting transformers, specifically designed for starting three-phase induction motors so as to eliminate supply voltage dips,
-   testing transformers, specifically designed to be used in a circuit to produce a specific voltage or current for the purpose of testing electrical equipment,
-   welding transformers, specifically designed for use in arc welding equipment or resistance welding equipment,
-   transformers specifically designed for explosion-proof and underground mining applications,
-   transformers specifically designed for deep water (submerged) applications,
-   medium Voltage (MV) to Medium Voltage (MV) interface transformers up to 5 MVA,
-   large power transformers where it is demonstrated that for a particular application, technically feasible alternatives are not available to meet the minimum efficiency requirements set out by EU REGULATION N. 548/2014,
-   large power transformers which are like for like replacements in the same physical location/installation for existing large power transformers, where this replacement cannot be achieved without entailing disproportionate costs associated to their transportation and/or installation.
For dry type large power transformers Minimum PEI values have been published in European Regulation and these values are included in Annex A.
NOTE 2   To retain consistency, the same list of exclusions in the EU Regulation N. 548/2014, has also been reproduced here. Within the above EU exclusion list, some had been excluded simply because no PEI data was available to CENELEC at the time on which to base appropriate PEI levels. Consequently, as such information becomes available in the future, it may be possible to derive suitable PEI Levels. Accordingly these particular categories are listed in Clause 6 as suitable for future consideration.

This European Standard covers medium power transformers. ‘Medium power transformer’ means a power transformer with a highest voltage for equipment higher than 1,1 kV, but not exceeding 36 kV and a rated power equal to or higher than 5 kVA but lower than 40 MVA.
National practices may require the use of highest voltages for equipment up to (but not including) 52 kV, when the rated voltage is less than 36 kV (such as Um = 38,5 kV or Um = 40,5 kV). This is considered to be an unusual case of a large power transformer, where the requirements are those for a medium power transformer with Um = 36 kV.
NOTE 1   ‘Large power transformer’ means a power transformer with a highest voltage for equipment exceeding 36 kV and a rated power equal to or higher than 5 kVA, or a rated power equal to or higher than 40 MVA regardless of the highest voltage for equipment. Large power transformers are in the scope of EN 50629.
NOTE 2   Transformers with tap changer (DETC or OLTC) are included in this European Standard even if they have separate tapping winding.
The object of this European Standard is to set up requirements related to electrical characteristics and design of medium power transformers.
The following transformers are excluded from this European Standard:
a)   instrument transformers, specifically designed to supply measuring instruments, meters, relays and other similar apparatus;
b)   transformers with low-voltage windings specifically designed for use with rectifiers to provide a DC supply;
c)   transformers specifically designed to be directly connected to a furnace;
d)   transformers specifically designed for offshore applications and floating offshore applications;
e)   transformers specially designed for emergency installations;
f)   transformers and auto-transformers specifically designed for railway feeding systems;
g)   earthing or grounding transformers, this is, three-phase transformers intended to provide a neutral point for system grounding purposes;
h)   traction transformers mounted on rolling stock, this is, transformers connected to an AC or DC contact line, directly or through a converter, used in fixed installations of railway applications;
i)   starting transformers, specifically designed for starting three-phase induction motors so as to eliminate supply voltage dips;
j)   testing transformers, specifically designed to be used in a circuit to produce a specific voltage or current for the purpose of testing electrical equipment;
k)   welding transformers, specifically designed for use in arc welding equipment or resistance welding equipment;
l)   transformers specifically designed for explosion-proof and underground mining applications;
m)   transformers specifically designed for deep water (submerged) applications;
n)   medium Voltage (MV) to Medium Voltage (MV) interface transformers up to 5 MVA;
o)   large power transformers where it is demonstrated that for a particular application, technically feasible alternatives are not available to meet the minimum efficiency requirements set out by the commission regulation (EU) No 548/2014;
p)   large power transformers which are like for like replacements in the same physical location/installation for existing large power transformers, where this replacement cannot be achieved without entailing disproportionate costs associated to their transportation and/or installation.
In case one of the last two exclusions is claimed, this should be documented at the signature of the contract with a declaration made by the customer.
NOTE 3   This standard covers the transformers under the Commission Regulation (EU) No. 548/2014 and gives additional specific guidance for single phase transformers, multi winding transformers and for transformers with OF or OD cooling systems, necessary for the correct application of energy efficiency requirements to these categories of transformers.

This Part of IEC 60076 defines sound pressure and sound intensity measurement methods
from which sound power levels of transformers, reactors and their associated cooling devices
are determined.
NOTE For the purposes of this standard, the term "transformer" frequently means "transformer or reactor".
The methods are applicable to transformers, reactors and their cooling devices – either fitted
to or separate from the transformer – as covered by the IEC 60076 and IEC 61378 series.
This standard is primarily intended to apply to measurements made at the factory. Conditions
on-site can be very different because of the proximity of objects, including other transformers.
Nevertheless, this standard is applied to the extent possible for on-site measurements.

EN 50629 applies to new three-phase and single-phase power transformers with a highest voltage for equipment exceeding 36 kV and a rated power equal or higher than 5 kVA, or a rated power equal to or higher than 40 MVA regardless of the highest voltage for equipment. The scope of this European Standard is the following: - Defining the appropriate energy efficiency criteria; - Setting of benchmark minimum efficiency levels for new transformers based on an assessment of the energy efficiency of the European transformer population installed in the last 10 years; - Proposing higher minimum efficiency levels for improving the energy efficiency of new transformers; - Providing guidance for consideration of Total Cost of Ownership. This European Standard provides also a form for efficiency data collection to inform future efficiency benchmark levels.

EN 50216-4 specifies basic accessories of transformers / reactors, such as
− Thermometer pockets, to be used for liquid immersed transformers,
− Earth terminals; to be used for liquid immersed and dry-type transformers,
− Draining plugs, to be used for liquid immersed distribution transformers,
− Filling openings, to be used for liquid immersed distribution transformers,
− Rollers, choice and distance to be used for liquid immersed and dry-type transformers.
After agreement between purchaser and manufacturer, this part of EN 50216 Series may still be
applicable either as a whole or in part to large power transformers or special transformers.

This European Standard illustrates the procedures that should be applied to evaluate the
uncertainty affecting the measurements of no-load and load losses during the routine tests on
power transformers.

This European Standard applies to new three-phase and single-phase power transformers with Um > 36 kV.
The scope of this European Standard is the following:
•   Defining the appropriate energy efficiency criteria;
•   Setting of benchmark minimum efficiency levels for new transformers based on an assessment of the energy efficiency of the European transformer population installed in the last 10 years;
•   Proposing higher minimum efficiency levels for improving the energy efficiency of new transformers;
•   Providing guidance for consideration of Total Cost of Ownership.
This European Standard provides also a form for efficiency data collection to inform future efficiency benchmark levels.
Transformers considered to be out of the scope of this document are the following:
•   Instrument transformers;
•   Earthing transformers;
•   Traction transformers on rolling stock;
•   Starting transformers;
•   Testing transformers;
•   Welding transformers;
•   Explosion-proof and underground mining transformers;
•   Transformers for deep water (submerged) applications.

This European Standard covers the oil-immersed single-phase connection assemblies of cables for
transformers and reactors designed in accordance with EN 60076 series.
NOTE The term "transformer" is used as common definition for transformer and reactor.
If no separate cable connection box is used and dry-type cable terminations are directly installed into the
transformer tank the requirements of this standard should be followed.
The purpose of EN 50299-2 is to establish for the cable connection assemblies:
• electrical and mechanical requirements including interchangeability;
• limits of supply;
• tests to be carried out.
It complements and amends, if necessary, the relevant standards and applies to dry-type cable terminations
for power cables with extruded insulation which may be used with similar interfaces for the cable entrance in
switchgear applications according to EN 62271-209.
This standard applies to oil-filled cable connection boxes of transformers with highest voltage for equipment
from Um = 72,5 kV to 550 kV, including the conductor current terminal with removable link between the
transformer and the dry-type cable termination.

This European Standard covers the oil-immersed single-phase connection assembly of cables for
transformers and reactors, designed in accordance with EN 60076 series.
NOTE In the standard the term "transformer" is used as common definition for transformer and reactor.
The purpose of EN 50299-1 is to establish for the cable assemblies:
• the electrical and mechanical requirements, including interchangeability;
• the limits of supply;
• the test to be carried out.
It complements and amends, if necessary, the relevant IEC standards and applies to oil immersed cable
connections, suitable for fluid-filled or dry-type cable terminations.
EN 50299-1 does not cover direct cable terminations (see 3.1.1.3), but, in this case, upon agreement
between purchaser and supplier, the standard may be used for guidance except for Figure 1 and Figure 2
which are not applicable.
This standard applies to oil-immersed cable connection boxes on transformers with highest voltage for
equipment Um = 72,5 kV to 550 kV, including the current conductor terminal at the cable sealing end of the
transformer.

EN IEC 60214-1 applies to on-load tap-changers of both resistor and reactor types, deenergized tap-changers, and their motor-drive mechanisms. It applies mainly to tap-changers immersed in mineral insulating oil according to IEC 60296 but may also be used for tap-changers with air or gas insulation or immersed in other insulating liquids insofar as conditions are applicable. It applies mainly to tap-changers with arcing contacts but may also be used for arcing-free onload tap-changers (such as electronic switching) insofar as conditions are applicable. This part of IEC 60214 applies to power and distribution transformers of all types and also to reactors. It does not apply to transformers and reactors mounted on railway rolling stock.

This International Standard applies to power transformers as defined by and in the scope of IEC 60076-1. It gives details of the applicable dielectric tests and minimum dielectric test levels. Recommended minimum external clearances in air between live parts and between live parts and earth are given for use when these clearances are not specified by the purchaser. For categories of power transformers and reactors which have their own IEC standards, this standard is applicable only to the extent in which it is specifically called up by cross reference in the other standards.

This part of IEC 60076 applies to liquid-immersed power transformers employing either hightemperature insulation or combinations of high-temperature and conventional insulation, operating at temperatures above conventional limits. It is applicable to: - power transformers in accordance with IEC 60076-1; - convertor transformers according to IEC 61378 series; - transformers for wind turbine applications in accordance with IEC 60076-16; - arc furnace transformers; - reactors in accordance with IEC 60076-6. This part of IEC 60076 may be applicable as a reference for the use of high-temperature insulation materials in other types of transformers and reactors.

This part of the IEC 60076 series covers the measurement technique and measuring equipment to be used when a frequency response measurement is required either on-site or in the factory either when the test object is new or at a later stage. Interpretation of the result is not part of the normative text but some guidance is given in Annex B. This standard is applicable to power transformers, reactors, phase shifting transformers and similar equipment.

This part of IEC 60076 applies to three-phase and single-phase power transformers (including auto-transformers) with the exception of certain categories of small and special transformers such as:
– single-phase transformers with rated power less than 1 kVA and three-phase transformers
less than 5 kVA;
– transformers, which have no windings with rated voltage higher than 1 000 V;
– instrument transformers;
– traction transformers mounted on rolling stock;
– starting transformers;
– testing transformers;
– welding transformers;
– explosion-proof and mining transformers;
– transformers for deep water (submerged) applications.
When IEC standards do not exist for such categories of transformers (in particular transformer
having no winding exceeding 1000 V for industrial applications), this part of IEC 60076 may
still be applicable either as a whole or in part.
This standard does not address the requirements that would make a transformer suitable for
mounting in a position accessible to the general public.
For those categories of power transformers and reactors which have their own IEC standards,
this part is applicable only to the extent in which it is specifically called up by cross-reference
in the other standard. Such standards exist for:
– reactors in general (IEC 60076-6);
– dry-type transformers (IEC 60076-11);
– self-protected transformers (IEC 60076-13);
– gas-filled power transformers (IEC 60076-15);
– transformers for wind turbine applications (IEC 60076-16);
– traction transformers and traction reactors (IEC 60310);
– converter transformers for industrial applications (IEC 61378-1);
– converter transformers for HVDC applications (IEC 61378-2).
At several places in this part it is specified or recommended that an 'agreement' should be
reached concerning alternative or additional technical solutions or procedures. Such
agreement is made between the manufacturer and the purchaser. The matters should
preferably be raised at an early stage and the agreements included in the contract specification.

This Part of IEC 61378 deals with the specification, design and testing of power transformers and reactors which are intended for integration within semiconductor converter plants; it is not applicable to transformers designed for industrial or public distribution of a.c. power in general. The scope of this International Standard is limited to application of power converters of any power rating. Typical applications are: thyristor rectifiers for electrolysis; diode rectifiers for electrolysis; thyristor rectifiers for large drives; thyristor rectifiers for scrap melting furnaces, and diode rectifiers feeding inverters for variable speed drives. The standard also covers the regulating unit utilized in such application as step down regulating transformers or autotransformers. The valve winding highest voltage for equipment is limited to 36 kV. This standard is not applicable to transformers for HVDC power transmission. These are highvoltage transformers, and they are subjected to d.c. voltage tests. The standards for the complete converter plant (IEC 60146 series, or other publications dedicated to particular fields of application) may contain requirements of guarantees and tests (such as insulation and power loss) for the whole plant, including the converter transformer and possibly auxiliary transformers and reactor equipment. This does not relieve the application of the requirements of this standard concerning the guarantees and tests applicable to the converter transformer itself as a separate component before being assembled with the remainder of the converter plant. The guarantees, service and type tests defined in this standard apply equally to transformers supplied as part of an overall converter package, or to those transformers ordered separately but for use with converter equipment. Any supplementary guarantee or special verification has to be specifically agreed in the transformer contract. The converter transformers covered by this standard may be of the oil-immersed or dry-type design. Unless specific exceptions are stated in this standard, the transformers comply with IEC 60076 series for oil-immersed transformers, and with IEC 60076-11 for dry-type transformers.

This part of IEC 60076 applies to dry-type and liquid-immersed transformers for rated power 100 kVA up to 10 000 kVA for wind turbine applications having a winding with highest voltage for equipment up to and including 36 kV and at least one winding operating at a voltage greater than 1,1 kV. Transformers covered by this standard comply with the relevant requirements prescribed in the IEC 60076 standards.

EN 50216-12 deals with fans for oil-to-air coolers used for transformers as well as fans used for blowing out radiators. Only fans operating axially are dealt with in this standard specification. This standard specification defines the dimensions and requirements for ensuring fan interchangeability and uniform fan assembly.

This part of IEC 60076 applies to liquid-immersed transformers, identifies power transformers according to their cooling methods, defines temperature rise limits and gives the methods for temperature rise tests.

EN 50216-9 deals with oil-to-water heat exchangers that means a heat exchanger for the cooling of the transformer oil using a forced oil circuit and a forced water circuit. The oil-side of the oil-to-water heat exchangers is not included in the scope of the Pressure Equipment Directive 97/23/EC according to Article 1, § 3.12. The water-side falls into Article 3, § 3 of the Pressure Equipment Directive, therefore the rating plate must not contain a CE sign according to Article 15 of the Pressure Equipment Directive. This standard establishes essential dimensions and the requirements to ensure interchangeability and adequate mounting of the oil-to-water heat exchangers.

EN 50216-10 describes oil-to-air heat exchangers that means a heat exchanger for the cooling of the transformer oil using a forced oil circuit and a forced air circuit. The oil-to-air heat exchangers are not included in the scope of the Pressure Equipment Directive 97/23/EC according to Article 1, § 3.12. This standard establishes essential dimensions and the requirements to ensure interchangeability and adequate mounting of the oil-to-air heat exchangers.

EN 50216-11 covers oil temperature and winding temperature (thermal image) indicators of the interchangeable mechanical (not electronic) type with contacts for use with liquid immersed power transformers and reactors for indoor or outdoor installation. This standard defines the characteristics of the instruments in order to ensure the interchangeability achieving the same performance. Except where otherwise specified or implied herein, oil and winding temperature indicators shall comply with the requirements of EN 50216-1.

This Technical Report illustrates the procedures and criteria to be applied to evaluate the uncertainty affecting the measurements of no load and load losses during the routine tests on power transformers. Even if the attention is especially paid to the transformers, the document can be also used for the measurements of reactor losses, when applicable.

This part of IEC 60076 applies to the following types of reactors: - shunt reactors; - series reactors including current-limiting reactors, neutral-earthing reactors, power flow control reactors, motor starting reactors, arc-furnace series reactors; - filter (tuning) reactors; - capacitor damping reactors; - capacitor discharge reactors; - earthing transformers (neutral couplers); - arc-suppression reactors; smoothing reactors for HVDC and industrial application; with the exception of the following reactors: - reactors with a rating less than 1 kvar single-phase and 5 kvar three-phase; - reactors for special purposes such as high-frequency line traps or reactors mounted on rolling stock. Where IEC standards do not exist for small or special reactors, this part of IEC 60076 may be applicable as a whole or in part.

This Report provides guidance for the evaluation of electromagnetic fields around power transformers. This Report applies to power transformers covered by EN 60076 series with the following characteristics:;apparent rating P: 5 kVA P 1 000 MVA;insulating level, according to EN 60076-3: high voltage winding: Um from 7,2 kV to 525 kV low voltage winding: Um up to 525 kV Reactors are excluded from the present Report. Continuous conducted and radiated emissions are considered for power transformers operating under nominal working conditions of voltage and current. Fault conditions and low occurrence transient events, such as;short-circuits,;lightning and switching transients,;overloads (inrush currents, etc.),;overvoltages,;tap-changer operations, are not considered as normal working conditions. Immunity conditions are considered to ensure the power transformer operates as intended in its normal working environment. The immunity capability of the power transformer is considered for steady state and transient working conditions.

This part of IEC 60076 applies to high-voltage/low-voltage self-protected liquid-filled and naturally cooled transformers for rated power 50 kVA to 1 000 kVA for indoor or outdoor use having a - primary winding (high-voltage) with highest voltage for equipment up to 24 kV; - secondary winding (low-voltage) with highest voltage for equipment of 1,1 kV. These transformers are equipped with a self-protection and disconnection device to protect the environment, property and people and prevent any disturbance of the high-voltage network from the consequences of an internal transformer fault. Transformers covered by this standard comply with the relevant requirements prescribed in the IEC 60076 series. The self-protected transformer may be used in conjunction with other devices to provide system coordination and sensitive system protection. The protection system is not designed to be functional when the power supply is from the low-voltage side. The self-protected transformer is not intended to function in parallel with another transformer.

Supersedes EN 50216-5:2002/A1:2002

Supersedes EN 50216-3:2002/A1:2002

This part of IEC 60076 identifies the requirements for power transformers to sustain without damage the effects of overcurrents originated by external short circuits. It describes the calculation procedures used to demonstrate the thermal ability of a power transformer to withstand such overcurrents and both the special test and the theoretical evaluation method used to demonstrate the ability to withstand the relevant dynamic effects. The requirements apply to transformers as defined in the scope of IEC 60076-1.

Amendment A2 added to standard EN  50216-5 an information about operating limits  and using the pressure relief devices and  dehydrating breathers for power transformers.  It fixed dimensions of flanges and electric  contacts characteristics of pressure relief  devices, it gives a typical size classes of  dehydrating breathers.

This standard covers the butterfly valves used on the pipelines, in which the insulating liquid of power transformers or reactors flows, in order to allow the replacement of components, without removing the whole or a large amount of the insulating liquid from the conservator and the tank. This standard defines the general overall dimensions and some functional and manufacturing characteristics to guarantee interchangeability.